Erratic Idle, Injectors spraying without the engine running, unequal flow from injectors usually means an overhaul is required.
Kits are available to match the part number on the CIS or if you prefer, get the parts individually.
I bought a kit and it comes with different seals for variants and not all are used.
A new metal diaphragm is also included in a kit.

*do not twist, use any levers or damage the mating surfaces, a few light taps on the outside with a hammer should be all that is needed.

You should now be at this stage.

Pull off the centre cylinder and remove the piston if it has not already been removed.

There are 6 ‘O’ rings here to be replaced, check the small fuel filter and remove and clean if necessary.
Check movement of piston in the cylinder and very lightly sand if necessary.

There is an ‘O’ ring in the base, a bit tricky this one.

And one final ‘O’ ring in the pressure relief valve (may be different for USA models)
Shims may be needed to adjust system pressure later.
System pressure should be between 65-75 psi.

Insert the piston back in the top section, using plenty of lube, wd40 or oil, aligning the mark with one of the outlets.
Fit the new diaphragm and reassemble.

There you have it, a lot simpler to do than expected; on a scale of 1-10 I’d give it a 5._________________Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Result after setting the a/f mix -
smooth idle, easy start, no misfire, pulls well.
I think this is the best it has run since I bought it.
Still have a hot start problem but can live with that._________________Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

maybe a fluke but haven't had any problems.
Make sure everything is clean especially the mating surfaces._________________Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

If you're going to use 1200 paper. Way back when we had to repair industrial piston type air compressor valves(called reed valves I think) the technique was to put the paper on a sheet of plate glass. then take the valve part with a little oil on it and sand it using a figure 8 motion. The figure 8 motion tends to equalize all the little natural pressure variations from pushing it around. I'd practice first using some Prussian Blue on a chunk of steel. It was pretty tricky to do correctly, but got a surface better than a surface grinder.